每个丝裂原活化蛋白激酶（mapk）途径的中心核心是3种蛋白激酶的保守级联：活化的mapk激酶（mapkk）磷酸化并激活特定的mapk激酶（mapkk），然后激活特定的mapk。当erk-mapks被有丝分裂刺激激活时，csbp2和jnk-mapks被渗透性休克、紫外线照射、创伤应激和炎症因子等环境胁迫激活。这个基因编码一种mapkkk，mekkk4蛋白，也称为mtk1。该蛋白在C末端含有蛋白激酶催化结构域n-末端非激酶结构域可能包含一个调控结构域。mekk4在哺乳动物细胞中的表达激活了csbp2和jnk-mapk途径，而不是erk途径。体外激酶研究表明，重组mekk4能特异性磷酸化并激活prkmk6和分别激活csbp2和jnk的serk1、mapkks，但不能磷酸化激活erk的mapkk。mekk4是激活csbp2-mapk通路的环境胁迫的主要介质，也是jnk通路的次要介质。已经描述了几种编码不同亚型的选择性剪接转录本[由RefSeq提供，2014年5月]
The central core of each mitogen-activated protein kinase (MAPK) pathway is a conserved cascade of 3 protein kinases: an activated MAPK kinase kinase (MAPKKK) phosphorylates and activates a specific MAPK kinase (MAPKK), which then activates a specific MAPK. While the ERK MAPKs are activated by mitogenic stimulation, the CSBP2 and JNK MAPKs are activated by environmental stresses such as osmotic shock, UV irradiation, wound stress, and inflammatory factors. This gene encodes a MAPKKK, the MEKK4 protein, also called MTK1. This protein contains a protein kinase catalytic domain at the C terminus. The N-terminal nonkinase domain may contain a regulatory domain. Expression of MEKK4 in mammalian cells activated the CSBP2 and JNK MAPK pathways, but not the ERK pathway. In vitro kinase studies indicated that recombinant MEKK4 can specifically phosphorylate and activate PRKMK6 and SERK1, MAPKKs that activate CSBP2 and JNK, respectively but cannot phosphorylate PRKMK1, an MAPKK that activates ERKs. MEKK4 is a major mediator of environmental stresses that activate the CSBP2 MAPK pathway, and a minor mediator of the JNK pathway. Several alternatively spliced transcripts encoding distinct isoforms have been described. [provided by RefSeq, May 2014]